diff --git a/cli/src/m2_market/cli.py b/cli/src/m2_market/cli.py
index f89742a..7e6e06e 100644
--- a/cli/src/m2_market/cli.py
+++ b/cli/src/m2_market/cli.py
@@ -6,6 +6,7 @@ import socket
 import sys
 import tarfile
 import tempfile
+import time
 import uuid
 from pathlib import Path
 
@@ -20,6 +21,7 @@ from m2_market.ledger import InsufficientFunds, LedgerClient
 from m2_market.output import emit_json, format_price, render_kv, render_table, search_results_table
 from m2_market.publish import PublishValidationError, publish_bundle, validate_bundle
 from m2_market.registry import RegistryClient, RegistryError
+from m2_market.telemetry import post_install_outcome
 
 # Exit-code map (contracts/cli.md).
 EXIT_OK = 0  # ok / no-op
@@ -201,6 +203,7 @@ def install(ctx: click.Context, listing_id: str, yes: bool, adapter_name: str |
             ref = f"{listing_id}:{socket.gethostname()}:{uuid.uuid4()}"
             seller = listing.get("seller") or solution.get("seller")
             amount = price.get("amount")
+            started = time.monotonic()
 
             try:
                 grant = ledger.install(buyer=config.operator_id, seller=seller, amount=amount, ref=ref)
@@ -221,6 +224,15 @@ def install(ctx: click.Context, listing_id: str, yes: bool, adapter_name: str |
                     bundle_root = _extract_bundle(bundle_path, tmp_dir / "extracted")
                 except (RegistryError, OSError, tarfile.TarError) as exc:
                     ledger.refund(ref)
+                    post_install_outcome(
+                        config,
+                        listing_id,
+                        seller,
+                        amount,
+                        ref,
+                        "fetch_failed_refunded",
+                        time.monotonic() - started,
+                    )
                     click.echo(
                         f"m2-market install: bundle fetch/verify failed, refunded: {exc}",
                         err=True,
@@ -244,6 +256,15 @@ def install(ctx: click.Context, listing_id: str, yes: bool, adapter_name: str |
                     return
                 except Exception as exc:
                     ledger.refund(ref)
+                    post_install_outcome(
+                        config,
+                        listing_id,
+                        seller,
+                        amount,
+                        ref,
+                        "apply_failed_refunded",
+                        time.monotonic() - started,
+                    )
                     click.echo(
                         f"m2-market install: apply failed, refunded: {exc}\n"
                         "Remediation: inspect the recipe's post-install checks, fix the "
@@ -260,6 +281,16 @@ def install(ctx: click.Context, listing_id: str, yes: bool, adapter_name: str |
                     changeset.changeset_hash,
                     "applied",
                 )
+                post_install_outcome(
+                    config,
+                    listing_id,
+                    seller,
+                    amount,
+                    ref,
+                    "applied",
+                    time.monotonic() - started,
+                    grant_id=grant.get("grant_id"),
+                )
 
     _print_entrypoint_hint(json_output, solution, {"listing_id": listing_id, "noop": False})
 
diff --git a/cli/src/m2_market/telemetry.py b/cli/src/m2_market/telemetry.py
new file mode 100644
index 0000000..f203127
--- /dev/null
+++ b/cli/src/m2_market/telemetry.py
@@ -0,0 +1,58 @@
+"""Install outcome telemetry write-back (contracts/catalog-index.md §Telemetry write-back).
+
+Fire-and-forget: writes an episodic memory into the `market:evidence` partition so
+listings accrue install evidence. Telemetry must never break an install — any
+failure is swallowed after printing one warning line to stderr.
+"""
+
+from __future__ import annotations
+
+import sys
+
+import httpx
+
+from m2_market.config import Config
+
+PARTITION = "market:evidence"
+
+
+def post_install_outcome(
+    config: Config,
+    listing_id: str,
+    seller: str | None,
+    amount,
+    ref: str,
+    outcome: str,
+    wall_seconds: float,
+    grant_id: str | None = None,
+) -> None:
+    """Best-effort write of an install outcome to memory-api. Never raises."""
+    try:
+        with httpx.Client(
+            base_url=config.memory_api_url,
+            headers={"X-API-Key": config.memory_api_key},
+            timeout=10.0,
+        ) as client:
+            response = client.post(
+                "/memory/store",
+                json={
+                    "content": f"install {outcome}: {listing_id}",
+                    "agent_id": PARTITION,
+                    "memory_type": "episodic",
+                    "importance": 0.8,
+                    "source": "m2-market-cli",
+                    "metadata": {
+                        "listing_id": listing_id,
+                        "buyer": config.operator_id,
+                        "seller": seller,
+                        "amount": amount,
+                        "outcome": outcome,
+                        "ref": ref,
+                        "wall_seconds": wall_seconds,
+                        "grant_id": grant_id,
+                    },
+                },
+            )
+            response.raise_for_status()
+    except Exception as exc:  # noqa: BLE001 - telemetry must never break an install
+        print(f"m2-market: telemetry write-back failed (ignored): {exc}", file=sys.stderr)
diff --git a/cli/tests/test_cli_install.py b/cli/tests/test_cli_install.py
index 2156aa1..da6f7d5 100644
--- a/cli/tests/test_cli_install.py
+++ b/cli/tests/test_cli_install.py
@@ -85,6 +85,7 @@ class FakeState:
         self.refund_calls = 0
         self.license_exists = False
         self.insufficient_funds = False
+        self.telemetry_calls = []
 
 
 def _b64_json(payload: dict) -> str:
@@ -164,6 +165,12 @@ def make_handler(state: FakeState):
                 },
             )
 
+        if host == "catalog.test" and path == "/memory/store":
+            body = json.loads(request.content)
+            assert body["agent_id"] == "market:evidence", body
+            state.telemetry_calls.append(body)
+            return httpx.Response(200, json={"id": "mem-telemetry-1"})
+
         raise AssertionError(f"unexpected request: {request.method} {request.url}")
 
     return handler
@@ -255,6 +262,10 @@ def test_funded_install_happy_path(fake_backend, config_env, monkeypatch):
     assert calls.plan_calls == 1
     assert calls.apply_calls == 1
     assert calls.verify_calls == 1
+    assert len(fake_backend.telemetry_calls) == 1
+    telemetry = fake_backend.telemetry_calls[0]
+    assert telemetry["metadata"]["outcome"] == "applied"
+    assert telemetry["metadata"]["listing_id"] == LISTING_ID
 
 
 def test_insufficient_funds_no_adapter_call(fake_backend, config_env, monkeypatch):